Honestly?
you're trying to sell an unknown amount of stuff, for a price that's likely close if not more to the price when on sale.
the fact that you don't know what equipment is there sort of indicates you didn't buy it initially either.
The fact that it's an AGA aquarium indicate it's a good few years old.
And any warranty you would expect on a new tank will not be valid here either.
If you want to try to get the most money from the sale, my suggestion would be to lower the price and sell the tank, stand, light and lid. and then sell any decor or equipment separately.
Take it out of storage, take better pictures, and verify that it holds water, because by your own admission you don't even know; What do you think will be the most important fact for someone looking to buy an aquarium?
It's not a collectible item, it's not going to gain value sitting around gathering dust in storage; the fact that you haven't tried to sell it here to people who know what it would be worth speaks volumes too.